Admin Login Error

I upgraded to WP 2.0, following the detailed steps for upgrading, and it appeared to be successful. My blog shows up fine, but if I try to login in as Admin to post, I get the following error:

Fatal error: Call to undefined function: __() in /home/stainedg/public_html/wp-admin/index.php on line 3

This is my second try at upgrading at 2.0, so I’m starting to get a little frustrated. Any help is much appreciated!